1. Field of the Invention
The invention relates to an electricity storage device that exerts a restraining force on a plurality of cells with the use of end plates.
2. Description of Related Art
In some cases, a plurality of unit cells are aligned in a direction when the plurality of unit cells are used to form a battery pack. A pair of end plates are placed at two ends in the direction of alignment of the unit cells and the end plates are used to exert a restraining force on the plurality of unit cells (see Japanese Patent Application Publication No. 2006-253149 (JP-A-2006-253149), for example).
In the case of a structure, in which the end plates are in contact with the unit cells, however, there is a fear that the temperature of the unit cells that are in contact with the end plates becomes lower than the temperature of the other unit cells that are not in contact with the end plates because the heat of the unit cells is transferred to the end plates. In this case, the temperature varies depending on the plurality of unit cells that constitute the battery pack.